Investigations of protective effects of the flavonoids quercetin and rutin on stress resistance in the model organism Caenorhabditis elegans.

Oxidative stress as a result of excessive generation of reactive oxygen species (ROS) or diminished antioxidative defence is regarded as a main factor in the pathophysiology of various diseases and ageing. Many flavonoids that are present in herbal edibles have antioxidative properties and possess a remarkable spectrum of biochemical and pharmacological actions. They are assumed to exert beneficial effects but the precise biological mechanism of their action is unknown. In this project, we studied effects of the flavonoids quercetin and rutin in the multicellular model organism Caenorhabditis elegans that exhibits a strong conservation in molecular and cellular pathways to mammals. Both flavonoids reduced the ROS accumulation at thermal stress and the extent of induced oxidative stress with quercetin having a stronger impact. The higher antioxidative activity of quercetin may explain the protection against lethal thermal stress and the reduction in accumulation of the ageing marker lipofuscin exerted by quercetin but not by rutin. The subcellular distribution of the FoxO transcription factor DAF-16 was only affected by quercetin indicating a modulatory effect of quercetin on signalling cascade(s). These results suggest that quercetin may act as an antioxidant as well as a modulator of cellular signalling processes to exert its protective properties.